The age, gender, weight, smoking history, assessment of pain, treatment type and co-morbid depression were also taken into account.

It was found that 8.9 per cent of patients over the age of 55 smoked, compared to 29.9 per cent of those aged 55 and younger.

Smokers reported to have greater pain than those who had never smoked. What's more, the average improvement in pain levels over the course of treatment was different in non-smokers and current smokers in both age groups.

It was revealed that those who quit smoking during their treatment reported greater pain improvement than those who continued on with the habit.